The present invention relates generally to vision testing equipment and methods, and more particularly to a novel instrument and method for the rapid and accurate determination of the accommodative amplitude and accommodative speed of the eye.
Accommodation is a clinical term referring to the ability of eyes to adapt or adjust to permit sharp retinal focusing of images of objects viewed at different distances. The maximum amount (or amplitude) of accommodation is a measure of near vision, or of how closely the eyes can see, without blurring. As the interocular muscles and the lenses age, and as the intraocular media change chemically (e.g., with age), accommodative speed and range will also change. Normally, a person will eventually require the assistance of bifocals or reading glasses to provide for the consequent impairment with age of accommodative powers of the eyes.
The present invention provides an instrument designed to rapidly and accurately measure both the amplitude and speed of accommodation of the eye, and to record the corresponding data on magnetic tape. The instrument is characterized by its simplicity and may be battery powered for portability. The instrument comprises a first visual display, preferably in the form of a diagonal square wave pattern on a flat light-emitting diode (LED) display, a lens having a focal plane coincident with the plane of the first display, a beam splitter, a movable second visual display having a selectable display configuration and whose image is reflected onto the optical axis of the lens by the beam splitter, and control means for randomly generating and positioning the second visual display configuration for measuring and recording information relating to the speed and amplitude of accommodation.
The instrument of the present invention may be useful for quantifying changes in accommodation as a result of the aging process or due to psychophysiologic factors occurring as a consequence of changing environmental factors.
It is, therefore, a principal object of the present invention to provide a novel instrument and method for measuring the speed of accommodation of the eye.
It is another object of the present invention to provide a novel instrument and method for measuring the amplitude of accommodation of the eye.
It is a further object of the invention to provide an instrument for measuring both the speed and amplitude of accommodation of the eye and which is portable and accurate.
These and other objects of the present invention will become apparent as the detailed description of certain representative embodiments thereof proceeds.